CC2592: Receiving sensitivity

Went Cao

Part Number: CC2592
Other Parts Discussed in Thread: CC2520, , CC2591

Dear All

I use CC2520 and CC2592 device, but if there is a 2.5GHz external interference signal, the receiver sensitivity of CC2520 will be reduced which useful signal is in 2400- to 2480-MHz,Why ? Is it normal ? Is there any measure to solve this problem ?

over 6 years ago

0 TER over 6 years ago

TI__Guru**** 317180 points

Please look into the blocking numbers for CC2520.

You write that you have an interferer at 2.5 GHz. At which level is this signal?

Do you see the same reduction in sensitivity regardless of which channel you use on CC2520? How much reduction in sensitivity do you see?

0 Went Cao over 6 years ago in reply to TER

Genius 5550 points

Dear TER
I think it because of CC2592 reduce the 2.4GHz signal, so I set this blocking number for CC2592.
My means is that my work signal is 2.4GHz, but when there is other 2.5GHz signal is coming, CC2592 receive 2.4GHz signal will be reduced so much.
CC2520 had received signals come from CC2592 lower 9dB than CC2591.

0 TER over 6 years ago in reply to Went Cao

TI__Guru**** 317180 points

Sorry, your last post is a bit hard to understand.

Do you mean the you get 9 dB reduction in sensitivity using CC2520+CC2592 compared to CC2520+CC2591 with all other parameters equal?

0 Went Cao over 6 years ago in reply to TER

Genius 5550 points

Dear TER
Yes, but it happen when there is 2.5GHz signal disturb.

0 behold li over 6 years ago in reply to Went Cao

Expert 2745 points

Do you confirm your CC2592 2.4Ghz frequency is work well in range of 2400~2483.5?

0 Went Cao over 6 years ago in reply to behold li

Genius 5550 points

Yes

0 TER over 6 years ago in reply to Went Cao

TI__Guru**** 317180 points

Do you have both a CC2520 + CC2591 and a CC2520 + CC2592 board? If that is the case, what is the sensitivity for the two boards (please provide also the measurement conditions as packet length, PER limit etc)

0 Went Cao over 6 years ago in reply to TER

Genius 5550 points

So in your test， there is no this measure？

0 Went Cao over 6 years ago in reply to Went Cao

Genius 5550 points

I had find the CC2520+CC2592 board received signal very low，because I do not have measure equipment ，so there is not data for it.

0 TER over 6 years ago in reply to Went Cao

TI__Guru**** 317180 points

If you haven't done any measurements, how do you then know it's a 9 dB difference?

0 behold li over 6 years ago in reply to Went Cao

Expert 2745 points

You need copy reference design first,and then attention P/N line 100 Ohm impedance match,and front of CC2592 single input 50 Ohm match.

0 Went Cao over 6 years ago in reply to TER

Genius 5550 points

9dB value,it is estimated, in other words, the received signal is very low so that impact our normal working.

0 Went Cao over 6 years ago in reply to behold li

Genius 5550 points

Dear Behold

Below is my PCB design,front of CC2592 single input 50 Ohm match.

0 Went Cao over 6 years ago in reply to Went Cao

Genius 5550 points

Dear TER and Behold

I add that I find bit error rate of CC2520 increases if there is 2.5GHz interference signal, but when I set a 2.5GHz filter SAW front of CC2592, the bit error rate of CC2520 is normal.

0 TER over 6 years ago in reply to Went Cao

TI__Guru**** 317180 points

Which SAW filter do you use? You write that you use a 2.5 GHz SAW filter but I assume the center frequency is 2440 MHz and hence improving the blocking.

As I wrote in my first post this is as expected since you have finite blocking. But without knowing the signal strength of your blocker etc it's difficult to comment further.

0 Went Cao over 6 years ago in reply to TER

Genius 5550 points

Dear TER

The 2.5GHz signal is coming from China Unicom 4G base station,which TD-LTE is 2555-2575 MHz.

0 Went Cao over 6 years ago in reply to TER

Genius 5550 points

Dear TER

The SAW filter is B9604,which brand is TDK.

0 TER over 6 years ago in reply to Went Cao

TI__Guru**** 317180 points

How strong the signal from the base station is depends on the distance from it but if the power is set high and you are close the blocking will be strong. The SAW filter you have tried attenuate the 4G signal with 50 dB- 60 dB which will give a much better performance with the presence of a blocker.

0 Went Cao over 6 years ago in reply to TER

Genius 5550 points

Dear TER

But the CC2591 device don't have this problem.
I want to know why does this CC2592 device have this problem , it means if I want to use CC2592, it need a SAW ?

0 Went Cao over 6 years ago in reply to TER

Genius 5550 points

Dear TER
Is there any update ? Thanks a lot.

0 TER over 6 years ago in reply to Went Cao

TI__Guru**** 317180 points

CC2591 and CC2592 are amplifiers, meaning that they should only affect the absolute level of blocking, not the relative. Meaning that if the blocking is 30 dB meaning that the blocker can be 30 dB above the wanted signal, the amplifier moves both the blocker and the wanted signal with the same amount. Meaning that the blocking is set by the CC2520. Why you see a difference is not possible for me to see without knowing the conducted performance of the two boards you use (sensitivity + blocking) it's not possible for me to know why you are seeing what you are seeing.

0 Went Cao over 6 years ago in reply to TER

Genius 5550 points

Dear TER

1. You said the blocking is set by the CC2520, could you share me how to set the CC2520 device ?
2. How to test the conducted performance of board ?

Thanks a lot.

0 TER over 6 years ago in reply to Went Cao

TI__Guru**** 317180 points

1) I wrote that the blocking is set by the CC2520, in other words itæs the blocking spec for CC2520 (given in the datasheet) that sets the blocking spec for the full system.

2) Some tips for measurements could be found in www.ti.com/.../swra603.pdf

Note when using a FEM (as CC2591/ CC2592 is) extra measurements should be done to ensure that the system is stable since adding an amplifier could cause instabilities.

0 Went Cao over 6 years ago in reply to TER

Genius 5550 points

Dear TER

1) I had check the CC2520 datasheet, but I can't find how to detailly set blocking spec , could you share me ?

0 TER over 6 years ago in reply to Went Cao

TI__Guru**** 317180 points

You find it under 5.5 in www.ti.com/.../cc2520.pdf as "interferer rejection"

0 Went Cao over 6 years ago in reply to TER

Genius 5550 points

Dear TER

I find the 5.5 in CC2520 datasheet,as below, but I can't open the [2] links, so I don't understand how to set register to change " ±5 MHz from wanted signal. [2] requires 0 dB" or other two.

Could you help me to change them ?

0 TER over 6 years ago in reply to Went Cao

TI__Guru**** 317180 points

This is not register settings. Basically blocking measurements are done by:
- Measure sensitivity
- Set wanted signal x dB above sensitivity limit (x depends on the standard)
- Apply a interferer at a given offset (in this case 5 MHz) and see how strong the interferer can be before loosing packets.

Go to https://standards.ieee.org and search for the standard.

0 Went Cao over 6 years ago in reply to TER

Genius 5550 points

Dear TER

I know it turn out to measurements be done, not to set by software.

In your opinion,I need to firstly test the conducted performance of the two boards ?

0 TER over 6 years ago in reply to Went Cao

TI__Guru**** 317180 points

Yes, you should do conducted measurements. When using range extender you should also check stability by doing at least a simplified version of a load-pull measurement.

0 Went Cao over 6 years ago in reply to TER

Genius 5550 points

Dear TER

"load-pull " ? What is meaning ?

0 TER over 6 years ago in reply to Went Cao

TI__Guru**** 317180 points

en.wikipedia.org/.../Load_pull

You can do this by using a line Stretcher/ phase shifter, see products from microcircuits etc.

0 Went Cao over 6 years ago in reply to TER

Genius 5550 points

Dear TER

Could you share your email to me ? Thanks a lot.

0 Went Cao over 6 years ago in reply to TER

Genius 5550 points

Dear TER

My email is went.cao@wpi-group.com
Please email to me , Thanks a lot.

0 TER over 6 years ago in reply to Went Cao

TI__Guru**** 317180 points

Send me a friend request if you want to discuss something on a private channel.

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CC2592: Receiving sensitivity